Question

Which of these interactions has negative effects?
(i) Predation
(ii) Mutualism
(iii) Commensalism
(iv) Parasitism

• A. $(i)$ and $(iii)$
• B. $(i)$ and $(iv)$
• C. $(ii)$ and $(iii)$
• D. $(i)$ only

Answer 1

Answer: (B)

Interaction between the communities or populations are essential components of the ecosystem. Some interactions are beneficial for the populations or some are harmful. Based on the nature of interactions, there are the following categories:

1. Agonistic or positive interaction leads to the benefit of both species of the community.
2. Antagonistic or negative interactions lead to the harm of one species, and the benefit of the other.
3. Neutral interaction is neither beneficial nor harmful for any species.

Depending on the type of population interaction, following categories are attributed:

• Mutualism is a positive interaction. This is beneficial for both the species. Symbiosis is a type of mutual interaction. For example, lichens, where the phycobiont and mycobiont are benefited mutually. In case of Mycorrhhizae also, the fungal partner and the root of higher plants are benefitted.
• Commensalism is an interaction in which one species (the epiphyte, in this case) is benefited, and the host plant is neutral. The commensal (epiphyte) cannot survive without the host, but it is not the case with host.
• Parasitism is a negative interaction in which the smaller parasite (tick) harms the mightier host (dog, in this case). There may be ecto-parasite (ticks on skin) or endoparasites (tapeworm in out gut).
• Competition is a negative interaction, which is mainly for food, shelter or mate. This can be seen in Balanus and Chathamalus.
• Predation is also a negative interaction in which the mighty predator feed (by harming) on the weaker prey. Like a sparrow feeding the seeds.